You'd think that Justin Bieber and Ariana Grande had the same manager or something. Oh, wait. Whatever. All that matters is that Wednesday night, for the second time in as many weeks, JB made a surprise appearance during one of Ari's shows -- this time in Los Angeles -- and blew the crowd away with another three-song mini-concert.

Grande's show at the Forum was buzzing along just fine when Justin hopped up and joined her on "Love Me Harder," and then hung around a bit longer to sing his song "Where Are You Now."

And, just like they did in Miami a few weeks ago, they ended the reunion with a duet on Bieber's 2012 hit "As Long As You Love Me."

Ronin 47/Splash News

Justin is slowly returning to the musical spotlight, and, as he tweeted on Wednesday, "working on music," thanked Ariana for the chance to shine and hinted that he's eager to get back out on the road.